Fig. 6. Comparison of the Otx upstream region in Ciona intestinalis and Halocynthia roretzi. Gray lines indicate the 5' genomic region of Otx genes. Boxes indicate exons; light and dark gray indicate the untranslated and translated regions, respectively. Blue lines indicate the transcription regulatory modules identified in each ascidian species; below the lines, the distribution of putative transcription factor-binding sites (colored small ovals) is indicated for each regulatory module. The name of the cell lineage in which lacZ transcripts were detected is indicated for each regulatory module. Color codes for transcription factors and the nucleotide sequences of their binding sites are indicated at the bottom. In Ciona, asterisks indicate sites conserved between C. intestinalis and C. savignyi.